This is the 30th most frequent Catalan word.
dos
The number two.
Here, 'dos' is a numeral adjective specifying the quantity of cats.
Tinc dos gats a casa.
I have two cats at home.
In this context, 'dos' again functions as a numeral adjective indicating a division into two portions.
Aquest llibre està dividit en dos parts.
This book is divided into two parts.
Once more, 'dos' is used as a numeral adjective to describe the number of predominant colors.